TV's most underrated current drama, "Southland" (9 p.m. Jan. 17, TNT; 4 stars) launches a fourth season of LA.-based cop stories churning with chases, murders and a police station confrontation so violent and realistic you'll feel like you experienced it firsthand.

The beauty of this series from Ann Biderman ("NYPD Blue"), Christopher Chulack ("Third Watch") and John Wells ("Shameless") is that no matter how electric the action is, "Southland" takes the time to powerfully reveal the lives and emotions of the LAPD officers involved.

Lucy Liu and Lou Diamond Phillips guest star this season and make an impact from the word go. Liu's Officer Tang is paired up with Michael Cudlitz's Cooper, who is out of rehab and is feeling fit after his back surgery. Phillips' Officer Ferguson and his cynical attitude run afoul of Ben McKenzie's Sherman immediately, leading to another lesson for the rookie Sherman.

As perfectly cast as the guest stars are, the core players--Cudlitz, McKenzie, Shawn Hatosy and especially Regina King--keep us coming back for more. They bring as much raw emotion and honesty to their roles as Biderman brings authenticity to chronicling the gritty details of being a cop. "Southland" brims with plot twists that never, ever feel contrived.